A rotary power tool, such as a screwdriver, typically includes a mechanical clutch for limiting an amount of torque that can be applied to a fastener. Such a mechanical clutch, for example, includes a user-adjustable collar for selecting one of a number of incrementally different torque settings for operating the tool. While such a mechanical clutch is useful for increasing or decreasing the torque output of the tool, it is not particularly useful for delivering precise applications of torque during a series of fastener-driving operations.